As an example of a head support device of a disk drive with a conventional floating type head, a head support device in a magnetic recording/reproducing apparatus such as a hard disk drive will be described in the following with reference to drawings. (Refer to, for example, Japanese Registered Patent Gazette No. 2894262, Japanese Open Patent Gazette: Japanese Laid-open Patent H6-259905.)
FIG. 29 is a top view showing the configuration of essential components of a conventional head support device and magnetic recording medium. In FIG. 29, head support device 291 comprises suspension 292 with relatively low rigidity, plate spring 293, and support arm 294 with relatively high rigidity, and there is provided slider 295 mounted with a magnetic head (not shown) on the underside of one end of the suspension 292.
Also, magnetic recording medium 296 is configured so as to be rotated by spindle motor 297, and when the magnetic recording/reproducing apparatus is in recording/reproducing mode, because of the balancing relation between the floating force given to the slider 295 due to the air current generated with rotation of the magnetic recording medium 296 and the activating force of the plate spring 293 of the head support device 291 which activates the slider 295 toward the magnetic recording medium 296, the slider 295 floats a fixed amount from the magnetic recording medium 296. That is, it is configured in that the magnetic head mounted on the slider 295 floats a fixed amount from the magnetic recording medium 296.
The head support device 291 is rotated about bearing portion 299 by the action of voice coil 298 disposed on the support arm 294 when the magnetic recording/reproducing apparatus is in recording or reproducing mode, and the magnetic head mounted on the slider 295 is positioned with respect to the desired track of the magnetic recording medium 296, thereby executing the recording or reproducing operation.
However, in the above conventional disk drive, when the support arm 294 and the suspension 292 connected thereto are rotated about the bearing portion 299 by the action of the voice coil 298, the locus of the magnetic head moving on the magnetic recording medium 296 is arcuate and small in diameter. Usually, the head gap of the magnetic head mounted on the slider 295 passes through the center of the bearing portion 299 and is vertical to the radial line of the head support device 291 that is the lengthwise center line of the support arm 294 and the suspension 292. Accordingly, the recording track recorded on the magnetic recording medium 296 is provided with an angle of skew in accordance with the rotational locus of the magnetic head [angle in the direction of gap length of the magnetic head against the tangential direction of the recording track (direction vertical to the direction of trackwidth), that is, an angle in the direction of track width of head gap of the magnetic head against the radial direction of the recording track]. In the case of a disk drive with small disk diameter, the relative speed of magnetic head as against the magnetic recording medium 296 is lowest at the innermost periphery of recording zone A of the magnetic recording medium 296, then the slider 295 is hard to float, and therefore, the setting is made so that the central point of the slider 295 corresponds to the innermost periphery of the recording zone A, and also, the position of the bearing portion 299 being the rotational center of the head support device 291 is set so that, at the central point of the slider 295, the tangent against the track at the innermost periphery of the recording zone A corresponds to a direction vertical to the gap width direction of the magnetic head mounted on the slider 295. Accordingly, as the magnetic head moves toward the outer periphery from the inner periphery of the recording zone A of the magnetic recording medium 296, the angle of skew against the recording track is increased.
For example,
when the radius of the innermost periphery of recording zone A of magnetic recording medium 296=4 mm,
the distance from the rotational center of bearing portion 299 of head support device 291 to the magnetic head=13.6 mm, and
the distance from the center of slider 295 in the gap length direction of the magnetic head to the head gap center of the magnetic head=0.6 mm, then
the angle of skew at the innermost periphery of recording zone A of magnetic recording medium 296 is θ0=8.627°.
On the other hand,
when the radius of magnetic recording medium 296=8.45 mm, the skew angle θ calculated isθ=18.183°.In this case, when it is configured in that the separate recording and reproducing heads are integrally formed as one magnetic head, the radial positions of the recording head and the reproducing head differ from each other on the magnetic recording medium 296. That is, the difference in radial position Δr is as follows:
suppose the center line interval between the recording head and the reproducing head is d=2 μm, then
the difference in radial position
                              Δ          ⁢                                          ⁢          r                =                  d          ×                      cos            ⁡                          (                              90                -                θ                            )                                                              =                  2          ×                      cos            ⁡                          (                              90                -                18.183                            )                                                              =                  2          ×          0.312053042                                        =                  0.624          ⁢                                          ⁢                      µm            .                              The greater the radial distance on the magnetic recording medium 296 becomes, the difference in radial position between the recording head and the reproducing head on the magnetic recording medium 296 becomes greater, and when the mode is shifted from reproducing to recording or from recording to reproducing as a drive disk, it will invite lowering of the positioning accuracy of the recording head or the reproducing head, thereby requiring accurate correction of positioning in accordance with the difference in radial position between the recording head and the reproducing head. Particularly, when the mode is shifted from reproducing to recording, it is required to quickly and accurately correct the positioning, or otherwise there arises a problem such that shifting the mode to recording causes the occurrence of trouble such as erasing or the like on the already recorded zone.
In order to lessen the skew, it is necessary to increase the distance from the rotational center of the head support device 291 to the magnetic head, but it is contradictory to the purpose of miniaturization, making it difficult to realize the intended miniaturization.
Also, if the skew of the recording head is increased, deflection will be generated between the magnetic orientation and the recording magnetic field in the circumferential direction of the initialized magnetic recording medium 296, causing the recording characteristics to be deteriorated.
The present invention is intended to solve the above problems and to reduce the size of the apparatus, and also, the object of the invention is to provide a head support device capable of decreasing the skew, a driving method for driving the device, and a disk drive using them.